21) Melanin serves to protect cells in the deeper layers : 1200459.
21) Melanin serves to protect cells in the deeper layers of the epidermis from ________.
B) melanocyte activity
D) ultraviolet radiation
E) keratin production
22) The observed differences in skin color reflect the levels of ________ production.
23) Exposure of the skin to ultraviolet light
A) can result in increased numbers of melanocytes forming in the skin.
B) can result in decreased melanin production by melanocytes.
C) can cause destruction of vitamin D3.
D) can slowly increase melanocyte activity.
E) has no effect on the skin cells.
24) When the body is overheated, the skin responds by
A) decreasing melanin production.
B) losing oxygen to surrounding tissues.
C) constricting blood vessels.
D) dilating blood vessels.
E) increasing keratin production.
25) When a person becomes “pale,” what is the physiologic basis?
A) The blood supply to the skin increases.
B) The number of red melanocytes in the skin increases.
C) Melanocytes increase production of red pigments.
D) The blood supply to the skin decreases.
E) Increased heat causes the skin to turn red.
26) What is the function of melanin?
A) It provides water-resistant properties to the integument.
B) It continuously divides to replace cells that are lost or shed at the epithelial surface.
C) It is converted by the kidneys into the hormone calcitriol.
D) It is required for the normal maintenance of epithelial cells.
E) It protects DNA from the damaging effects of ultraviolet radiation.
27) Which of the following conditions is the most common form of skin cancer?
C) squamous cell carcinoma
E) basal cell carcinoma
28) Epidermal cells synthesize this vitamin when exposed to sunlight.
A) vitamin D2
B) vitamin C
C) vitamin E
D) vitamin D3
E) vitamin A
29) The most severe type of skin cancer is most likely to develop from
A) nonpigmented epithelial cells.
C) pigmented basal cells.
D) nonpigmented dermal cells.
30) What is the composition of the papillary layer of the dermis?
A) dense, regular connective tissue
B) stratified squamous epithelium
C) reticular connective tissue
D) areolar connective tissue
E) dense, irregular connective tissue